Conventionally, as hybrid vehicle, one disclosed in Patent Literature 1 is known. This hybrid vehicle is comprised of an engine as a power source, a first electric motor and a second electric motor provided between the engine and drive wheels, a power storage device for storing electric power caused by the first electric motor and the second electric motor, and so forth. The first electric motor includes a stator, an intermediate rotor, and an inner rotor, which are concentrically arranged from a radially outer side toward a radially inner side.
The stator is formed by winding three-phase coils on an iron core. The stator has an annular shape in cross-section, and is fixed to a housing. Further, the intermediate rotor as well is formed by winding three-phase coils on an iron core, such that it has a smaller diameter than that of the stator and has an annular shape in cross-section. Furthermore, the intermediate rotor is mechanically connected to an output shaft of the engine via a speed-increasing gear, whereby it is driven by torque from the engine. Further, in an example illustrated in FIG. 2 of the publication, the inner rotor has permanent magnets arranged on an outer peripheral portion of an iron core thereof, and is mechanically connected to a rotor of the second electric motor, described hereinafter.
On the other hand, the second electric motor is formed by a three-phase synchronous AC machine, and includes a stator and a rotor. The stator is formed by winding three-phase coils on an iron core, such that it has an annular shape in cross-section, and is fixed to a housing. Further, the rotor has permanent magnets arranged on an outer peripheral portion of the iron core thereof, and is connected to the drive wheels via a drive shaft.
In the hybrid vehicle configured as above, demanded torque of the engine is determined according to the vehicle speed, an accelerator pedal opening, and a shift position, and torques generated by the first electric motor and the second electric motor, and the amount of electric power regenerated by the first and second electric motors are controlled according to the demanded torque, the rotational speed of the engine, and the charged state of the power storage device.
[Patent Literature 1] Japanese Laid-Open Patent Publication (Kokai) No. 2000-197324.